Abstract: Population aging in China, which began in 2005, is still in its initial stage at present, while Population aging in Japan, which began in the middle of the last century, has been into the stage of super-aging society. Regional evolution of Population aging in China obviously depends on the regional economic development, while Population aging in Japan, on the other hand, is more and more dependent on the area-equalization degree of social security conditions. Through contrast and analysis of characteristics of population aging regional evolution in the two countries, this paper finds that: the characteristics and dominant factors of population aging regional evolution in different stages are great different, including: (1) the regional economic development plays an decisive role in its initial stage, while social security condition becomes the leading factor of aging population agglomeration in the later stages; (2) the effect of regional economic development on population aging, mainly manifests as labor migration between regions, while social security condition is more presented as top population aging, namely migratory aging.